Make preauth params work

If you specify a token and storage url when creating a Connection,
regardless of the auth api version the first request will be made
directly to swift.  You can either provide a preauthurl and preauthtoken
or fall back to os_options' object_storage_url and auth_token keys
(exposed as --os-storage-url and --os-auth-token on the command line or
OS_STORAGE_URL and OS_AUTH_TOKEN in the environment).

If a _retry wrapped request on a Connection fails because of invalid
authentication (401) the Connection's cached token and url will be
invalidated.  If the Connection's retries attribute is > 0 the
subsequent attempt will call get_auth to refresh the token, but the
pre-configured storage_url will always be re-used.  This is consistent
with current auth v2 behavior and less surprising for auth v1.

The pre-existing, but previously undocumented behavior/interface of
get_auth would override the storage_url returned by the auth service if
the 'os_storage_url' option was provided in the os_options dict.  To
ensure that this behavior is consistent across auth v1 and v2 from the
command line and when using the Connection class as a library - the
preauthurl is stashed in the os_options dict when provided.

Improved Connection.get_capabilities storage_url handling to better
support the consistent behavior of a preauthurl/object_storage_url on
the connection regardless of auth version.

Fixed up some test infrastructure to enable setting up and testing
multiple requests/responses.

Change-Id: I6950fb73f3e28fdddb62760cae9320e2f4336776
Merge "Make preauth params work"